Not the end of the world: Why Earth's
greatest mass extinction was the making of
modern mammals
28 August 2013
arisen as a result of the end-Permian mass
extinction - which wiped out 90 per cent of marine
organisms and 70 per cent of terrestrial species.
The research was conducted by the University of
Lincoln, UK, the National Museum in Bloemfontein,
South Africa, and the University of Bristol, UK, and
has been published today in Proceedings of the
Royal Society B.
Skeleton of the cynodont Galesaurus planiceps. Credit:
Roger Smith, Iziko Museums of South Africa Social
History / Natural History / Art Collections
Lead author Dr Marcello Ruta, evolutionary
palaeobiologist from the University of Lincoln's
School of Life Sciences, said: "Mass extinctions are
seen as entirely negative. However, in this case,
cynodont therapsids, which included a very small
number of species before the extinction, really took
off afterwards and were able to adapt to fill many
different niches in the Triassic - from carnivores to
herbivores."
Co-author Dr Jennifer Botha-Brink of the National
Museum in Bloemfontein, South Africa, said:
"During the Triassic, the cynodonts split into two
groups, the cynognathians and the
probainognathians. The first were mainly planteaters, the second mainly flesh-eaters and the two
groups seemed to rise and fall at random - first one
The first mammals arose in the Triassic period,
expanding, and then the other. In the end, the
more than 225 million years ago. These early fur
probainognathians became the most diverse and
balls include small shrew-like animals such as
Morganucodon from England, Megazostrodon from most varied in adaptations, and they gave rise to
the first mammals some 25 million years after the
South Africa and Bienotherium from China.
mass extinction."
The ancient closest relatives of mammals – the
cynodont therapsids - not only survived the
greatest mass extinction of all time, 252 million
years ago, but thrived in the aftermath, according
to new research published today.
They had differentiated teeth (incisors, canines,
molars) and large brains and were probably warmblooded and covered in fur – all characteristics that
stand them apart from their reptile ancestors, and
which contribute to their huge success today.
Co-author Professor Michael Benton added: "We
saw that when a major group, such as cynodonts,
diversifies, it is the body shape or range of
adaptations that expands first. The diversity, or
number of species, rises after all the morphologies
However, new research suggests that this array of available to the group have been tried out."
unique features arose gradually over a long span
The researchers concluded that cynodont diversity
of time, and that the first mammals may have
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rose steadily during the recovery of life following the
mass extinction, with their range of form rising
rapidly at first before hitting a plateau. This
suggests there is no particular difference in
morphological diversity between the very first
mammals and their immediate cynodont
predecessors.
More information: The paper 'The radiation of
cynodonts and the ground plan of mammalian
morphological diversity' by Marcello Ruta, Jennifer
Botha-Brink, Steve Mitchell and Michael J. Benton
is published in Proceedings of the Royal Society B
20131865 on 28th August, 2013.
Provided by University of Lincoln
APA citation: Not the end of the world: Why Earth's greatest mass extinction was the making of modern
mammals (2013, August 28) retrieved 15 June 2017 from https://phys.org/news/2013-08-world-earthgreatest-mass-extinction.html
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